Box-shaped 3D particle collision shape affecting [GPUParticles3D] nodes. Box-shaped 3D particle collision shape affecting [GPUParticles3D] nodes. [b]Note:[/b] [member ParticleProcessMaterial.collision_mode] must be [constant ParticleProcessMaterial.COLLISION_RIGID] or [constant ParticleProcessMaterial.COLLISION_HIDE_ON_CONTACT] on the [GPUParticles3D]'s process material for collision to work. [b]Note:[/b] Particle collision only affects [GPUParticles3D], not [CPUParticles3D]. The collision box's size in 3D units.